


Innosince Appendix: Altered Time

by MageOfLight



Series: Innosince [3]
Category: Undertale
Genre: Ecto-Genitalia, GASTER Tags;, M/M, Skeleheat, UL Sanster, first heat, prepare your heart friends, we're opening on a feels trip
Language: English
Status: In-Progress
Published: 2018-04-04
Updated: 2018-04-04
Packaged: 2019-04-18 06:52:48
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 8,016
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14207520
Author URL: https://archiveofourown.org/users/MageOfLight/pseuds/MageOfLight
Summary: Various What If one-shot scenarios related to the Innosince storyline. Summaries and full warnings on the Index Page.





	1. Index

1: Gaster  
Warnings: None. Gaster and Sans are fucking adorable as fuck. there's your warning. lmao  
Chapter Tags: prepare your heart friends, we're opening on a feels trip, UL Sanster, first heat, skeleheat, ecto-genitalia  
Summary:  
  
2: Infected  
Warnings: Honey being a fucking creep, Kidnapping, Drugging, Rape, Torture, uh... not actually done yet? so possibly more warnings to come. basically, this one is _bad_.  
Chapter Tags:   
Summary:  
  
3: Punishment  
Warnings: Flowey, Torture, dismemberment, Rape, More Torture, Flowey making Honey pay for his crimes, also not finished so more warnings may apply.  
Chapter Tags:   
Summary:


	2. Gaster

**Summary for the Chapter:**

> What would happen if teenaged Sin had managed to save Gaster.
> 
> Please make sure to have read all of _Innosince: Act 1_ and maybe chapter 1 of the appendix before reading this to get the full FEELS impact.

**Notes for the Chapter:**

> most of this was written while zombified on medication and worse, a ton of it was written on my phone, so i'm not sure of the quality??? only going through enough to make sure it makes sense grammatically, so i apologize if this one is weird. X_X

Sans spun around at the sound of Gaster's surprised yelp and for a moment, he froze, sockets wide as Gaster crashed into the guardrail. He could hear it creak ominously and that shook him from his stupor. "don't move!" the small skeleton cried out and Gaster froze at the sharpness in his intern's voice. Blue magic seized Gaster's soul, but due to Sans' unstable emotions, it was only just strong enough to hold him in place as the rail creaked and started to give under his weight.  
  
"Sans... It is okay. Relax and keep calm," Gaster said, raising his voice just enough to cover another creaking snap. Sans could do this, he knew, but not if he was panicking. Sans seemed to take comfort in the older monster's calm tone because he took a deep breath, visibly calming which granted more strength to his magic. Focusing hard, Sans made a sharp tugging motion with his hand, his left eye flaring with flickers of purple and green magic and Gaster found himself sprawled on the floor two feet from the weakened railing.  
  
"boss! are you okay?!" Sans asked, rushing over and hovering worriedly.  
  
"Thanks to you, I am indeed fine. Well done, Sans. I knew you could do it," Gaster replied as he pushed himself up. Sans had panicked tears rolling down his cheekbones when Gaster took in his appearance to make sure Sans was okay as well and he frowned upon seeing them. "Oh dear..." he murmured, then opened his arms. Sans fell into them with a sharp sob and Gaster pulled him in close, stroking his skull gently until Sans had managed to cry himself into a fitful doze. Gaster smiled sadly down at him, shifting the younger skeleton so that he could easily pick him up. Once on his feet, Gaster cast one last look at the rail that had nearly been the end of him and then left the room, already making plans for the entire rail to be removed and replaced. It wouldn't do to have another accident like that. Who knew what would happen if someone actually fell into the core.

\--------------------------------------------

Gaster grinned down at the stunned young monster next to him as he stared around the room that was fully decorated for a party. There was a banner stretched across the back wall with the word "HERO" written on it in papyrus font with Sans' face drawn underneath. The young skeleton that was the source of that looked extremely pleased with his work as he bounded across the room to give a leaping hug to his older brother. Sans couldn't help the startled laugh that escaped him as he caught Papyrus up in blue magic to soften the blow. With his little brother now clinging to him, Sans looked up at Gaster with a slightly furrowed brow. "what's this all about?" he asked, confused. Gaster laughed softly, patting Sans' shoulder.  
  
"You are a hero now, Sans. I wanted to thank you and the rest of the lab figured that you deserved a party. It is not every day that someone has the quick wit to save another from a situation like that. If not for you being there, I would likely be dead right now," Gaster replied.  
  
"Indeed. Actions such as yours should be commended, my boy," a deep, jovial voice said from behind them. Sans froze. He knew that voice. It was hard not to, given who it belonged to. The king was here. _The king was here!_  
  
"FLUFFY!" Papyrus announced and Sans flinched along with their parents at Papyrus' complete lack of filter.  
  
However, King Asgore just laughed and replied, "That's King Fluffybuns to you, my child." Gaster and some of the other older monsters laughed along with the king as Papyrus released Sans so that he could turn around and look up, up, and up at the massive king. Asgore barely fit in the room, stooping down to avoid raking his horns on the ceiling. "I am afraid I cannot stay long, but I came to see the little hero myself and personally extend my deepest thanks for saving the life of my dearest friend," he said, kneeling down to be closer to Sans' level.  
  
"Thank you. From the deepest layer of my soul, I thank you, Sans," Asgore said. "There is no way a simple medal can ever convey my gratitude, but let it be a reminder to you in dark times that you are strong, brave, and kind," he added, pinning a medal on the front of Sans' lab coat. Looking down in stunned silence, Sans noted that there was a small crystal embedded in the center of the disk of silver that made up the medal. When he looked back up, Asgore was sporting a gentle smile and Sans couldn't help but smile back.  
  
"t-thank you, king asgore," Sans murmured. He didn't think he really deserved any special attention like this, considering he'd just done what needed to be done. Heck, he'd been panicking and Gaster had needed to encourage him to calm down for him to have even managed the magic needed to pull the much bigger monster to safety. As much as he wanted to say that, though, he couldn't refuse Asgore's kindness either... and so he kept his mouth shut. Asgore gave him a knowing, yet proud look, then stood.  
  
"I must go now, but Sans, there is something that we need to discuss later. I shall call for you when it is time," he said, then turned to Gaster, patted him on the shoulder with his massive furry hand, then left, stooping even lower to fit through the door.  
  
Sans could only stand there in shock as the room exploded to life around him. He was shuffled to the middle of the room where he was seated in Gaster's favourite over-stuffed chair, which tended to be the seat of honour for birthday parties or celebrations of some important breakthrough or another. He hunched in on himself a little, disliking being the center of attention to such a large crowd of people, but Gaster and his parents were kind enough to keep him from being overwhelmed by too many people crowding him at once.  
  
Still, by the time it was over, he was exhausted and massively peopled out. "Are you all right, Sans? I am sorry about how many people showed up. It was supposed to be just myself, your family, and a couple of our closer co-workers," Gaster said, kneeling down to look Sans in the face. He noted how Sans' eyelights were barely lit, and how close to sleep he was and sighed, standing. "Verdana, Tahoma, would you be terribly bothered if Sans stayed here tonight?" he asked, looking at Sans' parents. Both scientists looked between themselves for a moment, then Verdana looked back to Gaster with a soft sigh.  
  
"yes, i do believe that might be for the best. Papyrus is still, well," she paused, glancing over at the thirteen-year-old who was still so wired from the party that he could hardly hold still, bouncing slightly on his feet and only being held back from once again leaping at his brother by Tahoma's hand holding his. "frankly, i had forgotten just how bad Sans is in a crowd. he's been doing so well here that it was easy to have it slip my mind... and with how exhausted he is right now, i think having Papyrus being so rambunctious would just tire him out more." She was smiling fondly despite her clear worry, and Gaster smiled back.  
  
"Good. We shall see you tomorrow, then," he said, and Verdana nodded back before taking her youngest son's free hand.  
  
"see you tomorrow, Dr. Gaster," she said and then the family was gone in a crack of teleportation magic courtesy of Tahoma.  
  
Once they were gone, Gaster turned to Sans who'd slumped a little in the chair, having dozed off while he and the elder Serifs were conversing. Laughing softly, he knelt next to the chair and reached out to shake the teen's shoulder. "Sans. Wake up," he murmured.  
  
Sans jolted slightly, jerking awake with a sleepy, "...wha...?" His dim eyelights met Gaster's and then he flushed as he seemed to have realized he'd fallen asleep. "s-sorry, i'll just-" His words cut off as he realized the room was entirely empty aside from him and Gaster. "b-boss? where'd everyone go?" he asked quietly, looking around, likely trying to see where his family vanished to.  
  
"Verdana and Tahoma took Papyrus home. I offered to let you stay with me for the night so you can get some proper rest," Gaster replied, standing and offering his hand to Sans to help him up. Sans flushed slightly as he took Gaster's hand, swaying a little once he was on his feet. Gaster was quick to steady him with a hand on his back, and Sans flushed a bit more, smiling up at the elder scientist.  
  
Once Sans was stable enough, Gaster let go and turned, motioning for Sans to follow. They walked for a little bit until they came to an area of the lab that Sans had never been in before. The Royal Scientist's personal quarters were usually off limits, so it was with great interest that Sans peered by Gaster as the door slid open. The space inside was warm and inviting with soft lighting that contrasted greatly with the nearly overly bright halls and rooms of the rest of the lab. Sans found himself instantly relaxing as he stepped inside at Gaster's inviting flourish of motion. "wow..." he murmured softly.  
  
"Yes, it is quite a nice little apartment, isn't it?" Gaster asked, a small note of pride in his voice at Sans' appreciation of the space. Sans shot him a relaxed grin and Gaster smiled back. "Come, allow me to show you to the guest room," he said and Sans followed once again as Gaster led him through the apartment to a hall in the back. They passed a washroom carved into the stone of the cavern itself, Sans noting when he looked inside that there was a simply massive bathtub taking up the entire back wall. He could probably swim in it easily. Gaster waited for him to finish snooping, then, with a look of amusement, led Sans to the next room over and pushed open the door. The room was somewhat small with most of its space taken up by a large bed covered in forest green bedding. The only other things in the room were a nightstand with a mushroom-shaped lamp that cast warm light when lit, and a small chest of drawers.  
  
"I am well prepared for guests. I am certain you will find something to wear to bed in your size in the drawers," Gaster told Sans, smiling as the smaller skeleton looked around the room.  
  
"thanks, boss," Sans replied, looking back with sleepily lidded sockets.  
  
"It is no problem, Sans. I am happy to provide a comfortable space for my favourite intern to rest comfortably," Gaster said, chuckling as Sans' cheekbones flushed a vivid purple. "Good night, Sans. Rest well," he said, then turned and left the room, smiling a bit more as Sans called out a stuttering good night of his own.

\--------------------------------------------

The next two weeks passed by in a blur, Sans eagerly waking, inhaling his breakfast, then teleporting to work on the off chance of seeing Gaster a bit early. He didn't even care that some of the other scientists were ribbing him about his obvious crush on Gaster. They didn't know the half of it, anyway, so he just met their playful teasing with jokes and puns, not even bothering to deny anything. He was in love with W.D. Gaster and there was no ignoring that fact.  
  
And there was also no ignoring the way that Gaster did not rebuff his flirting. Sometimes Sans even thought he caught sight of a faint blush, though that could have been wishful thinking.  
  
This morning was different, though. He woke to his alarm as usual, but something was... off. His bones felt abnormally warm, and instead of waking bright-eyed and chipper, he felt slow and lethargic. He groaned lowly, wondering if he was, perhaps, coming down with something. He absolutely hated getting sick. Still, he didn't feel that bad, so he hauled himself out of bed, pulled on his clothing for the day, then headed down for breakfast.  
  
"oh." The simple word in his mother's soft voice startled him, and he paused as he looked over at her. She had a look of pleased happiness on her face as she eyed Sans, though Sans couldn't figure out why, even as she grinned slyly and called out, "Tahoma, dear! bring the thing when you come down!"  
  
"...thing?" Sans asked, but Verdana just grinned wider. Moments later, there was the pop of teleportation magic, and his father, carting a large, gift-wrapped box, appeared. He took one look at Sans, let out a faint, wheezing chuckle, then dropped the box at Sans' feet.  
  
["CONGRATULATIONS, SANS,"] Tahoma signed, and Sans blinked at his parents in confusion.  
  
"just open it, Sans," Verdana said in mild exasperation. "if you don't realize what's going on now, you will once you see what's inside," she added, now looking amused.  
  
Sans blinked again, still baffled, but he turned his attention to the box. He spent a little time carefully working the paper open until he could slide it off and away without ripping it, a habit he'd picked up from his patient mother. Once that was out of the way, he opened the box and blinked at the contents. Inside was a pile of carefully folded fabric. Still confused, he picked up the topmost piece, letting it unfold to reveal it was a solid deep green turtleneck shirt. It took only seconds for all the pieces to fall together in Sans' mind. Waking up overly warm and lethargic. His mother's glee at seeing him. His father's congratulations. The box of shirts that, if he looked through, would all be utterly devoid of stripes.  
  
He was starting his first heat. Sans flushed brightly, hiding his face behind the shirt as Verdana cackled at his embarrassment. "go change your shirt, Sans. you're an adult now," she said after taking a moment to compose herself. Sans pulled the shirt away from his face, looking down at it. Just like that, he was an adult. It felt strange, knowing he was about to be leaving his stripes behind, but... He felt a slow grin take over his face as he took the shirt in his hands and teleported upstairs. He could look through the rest of his new shirts later.  
  
When he returned downstairs, the box had already been moved from the kitchen, likely sitting on the landing outside his room. "well? how do i look?" he asked, and his mother turned back to him, tears filling her sockets.  
  
Verdana let out a slow breath. "like an adult. it suits you, Sans," she said softly. "now, your heat will take a while to set in completely. you should be fine to go to work, but after that you should seek out a partner. though Dr. Gaster might actually dismiss you early if your scent sets in while at work," she said, and Sans nodded. He knew exactly who he wanted his heat to be passed with, but he didn't say anything about it to his mother. That was just too embarrassing. Bad enough that they had a gift box full of new shirts for him, just waiting for the first signs of his heat setting in. He didn't want to discuss his potential love life with them, too.  
  
Verdana looked amused by something, but he ignored it as she set a plate of pancakes in front of him. He practically inhaled them as was normal, then stood. "thanks, mom," he said, smiling. Then he kissed her on the cheek, receiving a kiss on the forehead in return before he teleported to work. He appeared in the lobby as usual, getting a double-take from the receptionist as he tried to quickly get past her without drawing any attention to himself. He failed, of course, as she gave a playful catcall and a teasing congrats. He flushed and rushed into the locker room to grab a clean lab coat. He didn't normally button them up, and it would look suspicious, but he really didn't want to be teased all the way down to Gaster's labs, so he did it anyway. With the buttoned coat hiding his new shirt's lack of stripes, he hurried to the elevator and down into the labs proper.  
  
He passed a few other early risers, rushing by them so quickly that they hardly had time to note that he was there, let alone that his coat was closed. By the time he made it to the deepest part of the labs where he and Gaster worked, he was out of breath and feeling hotter than previously. He nearly groaned at the thought that his rushing about had made his heat set in further, but he pushed back the urge as he approached Gaster, who was, as usual, already elbow deep in an experiment, one of his magically created extra hands writing notes that Sans would have to clean up and rewrite later. He never minded it, even if Gaster's handwriting could be a literal pain to read at times.  
  
However, this time when he approached, Gaster froze, back stiffening before he slowly pulled away from his experiment, turning to look at Sans. "Sans, you..." he murmured, taking in the sight of a faintly flushed Sans wearing a green shirt he'd never seen before with his coat firmly buttoned over it. His nasal ridge twitched slightly, obviously scenting the air and Sans found himself blushing harder. No way. Had his heat scent set in already? "...let me see your shirt," Gaster said instead of anything else Sans might have thought he was going to say. Sans thought about refusing, suddenly feeling shy about it, but... this was the monster he wanted to spend his heat with. Sans couldn't look childish. Not now of all times... so he reached up with mildly trembling hands and slowly undid his coat to reveal the solid green of his shirt.  
  
Gaster let out a soft breath, smiling. "Congratulations, Sans," he said simply, then almost reluctantly turned away. "Now-"  
  
"...boss?" Gaster stiffened again at the soft, hesitant way Sans said the word. There was a note of desperate hope in the word that had Gaster sighing.  
  
"Sans... I am... well aware of your crush on me... but you should probably find someone closer to your own age to spend your first heat with," the elder said, words holding a strange note of reluctance to them.  
  
In response, Sans took a deep, steadying breath. He had to be honest if he had any hope of getting the thing he wanted most. He couldn't hold back or he'd miss his chance. He just wished it would have been acceptable to talk about this sooner, but he'd still been in stripes, and who knew how long that would last. His first heat could have taken another 60 years, for all anyone knew. "it's not a crush," Sans stated firmly, flushing heavier at what he was implying with that statement. "it hasn't been a crush in a long time, honestly," he added, and Gaster whipped back around so fast that Sans thought he might over balance.  
  
"What are you saying, Sans?" the elder asked, and Sans swallowed.  
  
"i... i'm saying that i love you, w.d. gaster. i have for a few years now, but i couldn't say anything because i was still in stripes," Sans admitted, speaking slowly, nervous. "look, i get it if you don't feel the same way, but... i don't want to spend my first heat with someone closer to my own age. i've... i've been dreaming about spending it with you for ages." The confession felt like it took too much out of him, and he slumped slightly as Gaster's only reaction was to stare at him, slack-jawed.  
  
It took Gaster a bit longer than normal to pull himself together after such a bombshell, but once he did, he sighed, shaking his head. "...Sans... you should know better," he said softly. "While I am sure your parents would have no objection... and am almost just as sure that they have been trying to encourage this, you should know that we cannot. I am your boss, which creates a potential power imbalance-"  
  
"simple fix. i quit." Sans grinned impishly at the elder scientist who'd gone slack-jawed once again in surprise. "there, you're no longer my boss. no reason for anyone to fuss."  
  
Gaster shook off his shock, frowning. "No, Sans. I refuse to accept your resignation," he stated firmly. "You are much too smart to just abandon a job you love so much just because you-..." He cut himself off with a little sigh and a soft, wry smile. "However..." he murmured, then stood suddenly from his seat. "Sans, I must go out for a while. If you could get to work transcribing my latest notes, I would greatly appreciate it," he said, then briskly walked out of the room, leaving Sans standing there confused and disheartened.  
  
With a soft, sad sigh, Sans sat down at his desk and got to work. At least focusing on Gaster's sloppy penmanship would help keep his mind off the rejection.  
  
With his nasal ridge buried in Gaster's work notes and his own cleaned up versions of said notes, Sans lost track of time. The door sliding open made him jerk in surprise, but he refused to look up to face Gaster. He couldn't just yet. He'd get over it, but it still hurt. However, someone that wasn't Gaster cleared their throat and Sans looked up in surprised. Standing hunched over slightly to keep his horns from damaging the ceiling was none other than King Asgore Dreemurr. Sans dropped his pen in shock, standing up with wide sockets as Asgore's face lit up in a smile.  
  
"Hello again, Sans. I did intend to call you to the castle to talk, but Dr. Gaster informed me that talking here would be best, all things considered," the massive king said, and it was Sans' turn to stare with his jaw dropped open. "Gaster has given us permission to use his apartment to have this discussion. Sitting somewhere comfortable would be ideal, I do believe," he commented, and Sans snapped his mouth closed, nodding slowly to the king who smiled a bit wider. Together, the pair of them made their way to Gaster's apartment.  
  
Once there and seated comfortably in the sitting room, Asgore leaned forward to peer at Sans. "Firstly, I wish to congratulate you on getting out of your stripes," Asgore said with a soft chuckle. "I did suspect that you were on the cusp of adulthood. It's nice to know my instinct for such things has not failed me," he added as Sans flushed, burying his chin in the collar of his new shirt in embarrassment. Asgore's amused rumble of a laugh set him at ease again though. It reminded him of his parents for some reason. "Now, Gaster informed me that you two are in a bit of a predicament. You've fallen in love with him. And considering he came to me to help eliminate the power imbalance that would make him accepting your wishes illegal," Asgore paused as Sans flinched, "I highly suspect he's been harbouring growing feelings for you as well."  
  
"...you think so...?" Sans asked shyly, and Asgore smiled, reaching out to pat Sans on the shoulder.  
  
"I suspect. He at the very least wants to grant your request of helping you through your first," he replied, and Sans felt hope building in his soul again. "Now, considering he is currently your employer, there is no way he can do such a thing. That is why I am here. He's been gushing over just how smart you are for years, to be quite honest. Law dictates that a monster still in stripes can't be any more than an assistant, but now that you are officially an adult, I think it's high time for a promotion." Asgore paused once again, amused as Sans stared at him with comically widened sockets. "There is official paper work to be done yet, but you are here by promoted to Royal Scientist."  
  
Sans gaped. This was a big deal. While Gaster was still the chief Royal Scientist and owned the lab, each full scientist could work on whatever they wanted and were their own bosses. Of course, there were still issues in that Gaster was still the chief and owned the lab. He could put a halt to anything that went on there with a word. The thought made him frown. "but... that doesn't really solve anything. gaster's still the chief..."  
  
"That brings me to the other thing I wished to discuss with you," Asgore said with a sigh. "I had wanted to wait until the magic settled fully with you, but... perhaps now is the best time after all. Sans, have you heard of a monster known as the Judge?"  
  
"well, yeah... i kinda thought it was just a story to tell misbehaving baby bones, though," Sans replied, looking thoughtful. Asgore chuckled.  
  
"Well, there is indeed that story, but it's an exaggeration that came about when the Judge was a much more active role. The Judge is, in fact, a real monster. The magic passes on to a suitable recipient when the previous Judge passes. It chose you, Sans."  
  
Sans blinked. He didn't feel any different, but Asgore seemed absolutely certain. "You'll start to notice the changes in the coming weeks. I can sense where the magic has ended up, and it takes a while to settle with a new host. It chose you almost a year ago, but the Judge's magic cannot settle properly in a child. Your own magic was guarding you from that interference. Now that you are an adult, the magic will start settling. Your stats will drop. Attack and defence will settle out in the single digits but in return, your magic reserves will increase. You'll be able to see the souls of other monsters clearly if you focus and see their execution points and their LOVE as well as other private details." Asgore paused and sighed softly. "You won't be able to control it at first, so I'll need you to come stay in the castle until you can. Of course, you have the right to refuse the role of the Judge. Even if the magic has chosen you, I will not force you to take on such a responsibility."  
  
Sans looked down at the floor, eyelights hazing as he thought. After a few minutes, he looked back up at Asgore with a hum. "how often is the Judge even needed?" he asked and Asgore smiled at the question.  
  
"Monsters that require Judgement are few and far between. The Royal Guard is almost more a formality these days, to be quite honest. Captain Gerson only keeps the guard well trained to protect the people from fallen humans or to apprehend monsters who commit a crime, on the off chance that happens." Asgore sighed. "That aside, you do not need to decide what to do yet, Sans. Whether you act as the Judge or not, that is up to you. You should know though, that even if you decide not to, being the one chosen by the magic has placed you in a tier above even royalty. You answer to Dr. Gaster and myself as a scientist, but as the one chosen by the magic of the Judge, you answer to no one but yourself," Asgore told him, a slight smile on his face.  
  
"huh... king asgore, are you suggesting that... that evens things out? even if i decide not to ever use that magic?" Sans asked, canting his head slightly. Asgore simply winked in response, standing up.  
  
"Well, that was a lovely chat," Asgore said, patting Sans on the shoulder. "However, I am certain you are likely starting to become quite uncomfortable. I will inform Dr. Gaster that our discussion is over," the king said with a soft chuckle as Sans flushed, his entire face colouring with magic.  
  
"y-yeah... thanks king asgore," Sans replied quietly. He'd have a lot to think about once his heat was delt with, but the mention of the monster he'd fallen in love with worked pretty well to distract him from serious thoughts, his magic heating further in his bones. Once Asgore was gone, the small skeleton groaned, slumping in his seat. He was probably going to have to take care of this himself... but maybe he could entice Gaster to help while relieving some of the building heat at the same time...  
  
He didn't really think about it any further, simply hiking his shirt up his chest to let his fingers explore his bare bones. He'd never masturbated before, but instinct was a wonderful thing. He quickly found places on his rib cage that made him gasp, and curling his phalanges between his ribs to run them along the underside of his sternum pulled a soft moan from his throat. It felt so good and was so distracting that he didn't even notice the door opening, nor that he was putting on quite the show for Gaster, who'd frozen in the entryway.  
  
When he pressed harder against a particularly sensitive spot, he couldn't help it, arching and crying out Gaster's name, and Gaster responded with Sans' name in a breathy tone. That knocked Sans out of his pleasured daze, and he looked over, a vivid blush painting his face once again as he panted softly. Gaster was blushing as well, though his gaze was intense enough to send a bolt of arousal from Sans' soul to his pelvis, causing magic to pool there.  
  
Gaster breathed in deeply, seemingly entranced as he murmured, "Stars, but you smell amazing..." The scientist was leaning forward slightly, but then visibly reigned himself in, stepping back a little. "Sans... are you sure you really want me? I'm... so very old. The last thing I want to do is-"  
  
"gaster. i've been thinking about this for way too long already," Sans gasped, cutting the other skeleton off. "i've thought and argued this against myself for well over two years, and i always came up with the same answer. i want you to be my first. i want you to be... to be every time." Sans sat up straighter, letting his shirt fall back into place with a sigh. as much as he was insanely turned on and _really_ wanted to get off, they also needed to talk because Sans hadn't made himself clear. "i don't want... what everyone else seems to want. i don't want casual, Gaster. i want what mom and dad have. what the dog couple who live down the street has." He paused, taking a deep breath.  
  
"i want a mate, gaster... and i want that mate to be you," Sans said softly, looking away. There was no way that Gaster would want someone as young as him. He'd just been wearing stripes yesterday, and now he was barely an adult, telling one of the oldest monsters in the Underground that he wanted to be life partners. He was fully expecting to be laughed at, to not be taken seriously, but then Gaster was pulling him into a gentle hug.  
  
"You know... I always suspected that you were an old soul. You are so much more than many monsters your age," Gaster said with a soft sigh, rubbing a hand up and down Sans' back. "You remind me of the old days, before monster culture became so deeply rooted in sex. Sans, I cannot promise anything right now as we need to have a more serious discussion without... certain distracting things. Knowing that there are no promises on the table, do you still want me to help with your heat?" Gaster asked, pulling back to look Sans in the face, deep blue eyelights meeting hazy violet.  
  
Sans appeared to fight back the automatic urge to beg him, pulling back to sit on the other side of the couch where Gaster's body heat wouldn't be so distracting. He appeared to be at war with himself for a couple minutes, muttering under his breath as he tended to do when faced with a complicated problem during an experiment. Gaster couldn't help but smile fondly at seeing such a habit even here. As much as he didn't want to think about it right now with the scent of strawberries and vanilla making his own bones heat up, he could see himself in a relationship with Sans. It made him nervous though. Even with the promotion he'd asked Asgore to grant Sans so they'd be on more even footing, it still didn't balance things out well enough.  
  
On the other hand, Asgore had told him not to worry about it, that if he chose to pursue things with Sans, no one would have any cause to deem it taboo. Gaster still couldn't help but worry, though. Sans didn't seem to care one way or another. He was like a dog with a bone, willing to drop his dream job just to be with Gaster. While it brought warmth to his soul that Sans was willing to do that, he couldn't have allowed it. If they were going to do this, that sort of start would have just built resentment in the younger skeleton's soul.  
  
Gaster was knocked from his thoughts by Sans making a frustrated sound. "Sans?" he questioned, and the smaller sighed.  
  
"i... get that there are no promises here of something more, but... i can't... just give up on something i've wanted for so long. i still want my first to be with you, gaster," he said softly, sighing. There was still a note of hope in his voice that it wouldn't just be the first time, but Gaster nodded.  
  
"Very well," he responded, then stood. "Come, the couch is no place to do this," he said, holding out his hand for Sans. Sans beamed at him in response, his heat scent picking up in excitement as he took Gaster's hand.  
  
Gaster led the younger monster back to his bedroom, thumb rubbing circles into the back of Sans' hand the entire way. Once they arrived, Sans was already shivering in need, little breathy anticipatory sounds escaping his open mouth. "Before we start... do you have a safe word?"  
  
"...safe word?" Sans asked, looking confused for a second before he realized what Gaster was asking. "uh, yeah. not that we'll need it, but... it's 'snow'," he said, laughing softly.  
  
"Always better to be safe than sorry," Gaster replied, then leaned in and pressed a gentle kiss to Sans' mouth. Sans melted into it, moaning softly at the contact, hands coming up to cling to Gaster's labcoat. Gaster opened his mouth, tongue coming out to lick at Sans' teeth before slipping inside to tangle with Sans' tongue. The smaller skeleton moaned again, but this time much louder as Gaster explored his mouth, hands exploring his ribs through his shirt. A third hand slipped under the hem of his shirt to rub his spine and Sans gasped, jerking away from the kiss with a startled cry.  
  
Gaster chuckled, grinning down at Sans. "Don't tell me you forgot about these," he said, and Sans' eye sockets widened almost comically as he spotted Gaster's hand constructs.  
  
"...fuck," he hissed softly, then moaned as the one on his spine started massaging the bone, fingers pressing in just enough to send bolts of pleasure straight through him. "nn... gaster... please..."  
  
"I've got you, Sans," Gaster murmured, then ducked his head a little to lick and nip at Sans' cervical vertebrae, an action that earned Gaster another moan, the smaller's head tilting back to grant Gaster more access. Gaster couldn't help but smile at the look on Sans' face when he pulled away. "I know. But let's get some of this clothing off you. I'm sure it can't be comfortable with your heat."  
  
Sans gazed up at Gaster with hazed eyelights, seeming lost for a moment before comprehension dawned and he nodded, letting Gaster slide his labcoat from his shoulders. When the taller monster turned away to put the coat aside, Sans yanked his own sweater off, carelessly dropping it on the end of the bed. When Gaster turned back and took in his half-naked form, Sans took delight in the way his eyelights dilated and went momentarily hazy as well before sharpening in a look that was entirely predatory.  
  
"Sans," Gaster hissed and Sans felt a shiver run down his spine, heat blooming in his pelvis. Fuck, but he wanted Gaster so badly. Gaster seemed to echo the sentiment as he gently, yet forcefully pushed Sans back onto the bed, one knee coming to rest on the bed next to his hip to brace himself as Gaster leaned over him, hovering. Sans smiled, lifting his hands to rest on the back of Gaster's neck, tugging lightly until the elder skeleton obliged and met him in a kiss that Gaster was quick to dominate, leaving Sans to moan helplessly into his mouth as Gaster's hands drifted over his ribs, petting and stroking the bones to find his most sensitive places.  
  
All too soon, Sans was breaking the kiss to throw his head back with a gasping cry as Gaster's extra hands joined in, each one targetting overly sensitive spots. Another hand rubbed at his sacrum through his pants and Sans cried out again as his magic formed with a snap, glowing bright enough to shine through the thick black fabric. Yet another hand palmed at his magic and Sans arched sharply into the contact, gasping the other skeleton's name. He barely heard Gaster's soft curse over the rush of pleasure, but then the hands on his lower body moved away and he whined, looking down.  
  
Gaster's hands moved to his belt and Sans watched with eager anticipation as his belt was unbuckled, followed by the button and zipper of his pants being swiftly undone. That, however, was when Gaster paused, looking up at Sans' face. Indigo eyelights met hazy purple in askance and Sans could only respond with a breathy, "please," to which Gaster smiled and nodded. And then Sans' pants were tugged down and off, leaving him utterly exposed.  
  
"Fuck, you are so beautiful," Gaster whispered reverently, causing Sans to blush heavily in a way that being naked and in heat hadn't. Before he could muster up a reply, however, Gaster leaned in to lick at Sans, tongue tip flicking gently at Sans' clit while his extra hands got back to work. Sans could only writhe and cry out at the sensations, hands fisting tightly in the sheets as pressure built in his non-existant gut.  
  
Gaster worked him over with tongue, teeth, and way too many hands until, with a loud, sharp cry, the pressure released in a wave of brilliant euphoria that had his back arching.  
  
When he came down from his high, he found himself slumped weakly against Gaster's chest, the elder actually purring contentedly as he stroked Sans' skull. "mm... gaster..." Sans murmured, looking up. Gaster met his gaze with blown eyelights, a soft, deep-blue flush on his cheekbones and when Sans shifted, he could feel something hard and hot twitch in Gaster's pants. He was already pretty tired out by that first orgasm, but the feel of it sent a fresh wave of heat burning through him and he moaned softly, wanting to feel that inside him.  
  
Gaster chuckled, though. "Not yet, Sans. Sleep for now. We'll continue this once you've rested." Sans whined, but let himself relax against Gaster again, dozing but not really falling asleep. It was still restful, though, and when he woke properly, he couldn't ignore the burn in his bones any longer, nor the way his pussy fluttered around nothing as he ground down against the bulge in Gaster's pants.  
  
Gaster let out a surprised curse, then groaned lowly as he met Sans' next roll downward with a thrust up that had the tip of his clothed dick rubbing at Sans' folds in such a way that Sans keened at the sensation. "nn... please, gaster..." he moaned and Gaster growled softly. Sans soon found himself laying on his back on the bed again, Gaster's hand constructs rubbing at all his sensitive spots, another one slicking itself on the lips of his pussy before sliding a single phalanx in, slowly working him open as Gaster stepped back, finally beginning to shed his own clothing.  
  
By the time Gaster had gotten his pants off, Sans was already teetering on the edge again, four phalanges steadily working in and out of him with loud, wet sounds that both made him burn hotter and embarrassed him, though the second was mild, his mind too occupied with _want_. Gaster's dick looked huge and some distant, embarrassed part of him wondered how it was going to fit, but the rest of him keened out a desperate sound, reaching for the bigger monster, begging for him.  
  
Gaster cursed softly again, the construct thrusting into Sans pulling back and dematerializing so Gaster could get in there. Sans gasped and keened as Gaster rutted up against him, slicking his cock on Sans's fluids before lining himself up and stopping. "Are you sure it is me you want taking you for the first time?" he asked softly. Sans, too far gone for words, growled and hooked his legs up around Gaster's hips and used that leverage to tug, pulling Gaster in so that the tip of his cock slid inside. Sans gasped and moaned at the sensation, clenching around the head for a moment, making Gaster moan as well before he chuckled. "Okay, I shall take that as an enthusiastic yes," he uttered with a breathy laugh.  
  
Sans clung desperately to his partner as Gaster started up a gentle rolling motion, rocking in and out slowly to get him used to the feel of having Gaster's massive dick inside him. Being stretched out by Gaster's phalanges couldn't have prepared him for this completely, but the elder scientist moved slow enough that the stretch burned a little but didn't hurt, and by the time Gaster had hilted himself completely, Sans was a panting, moaning mess.  
  
"Are you okay, Sans?" Gaster asked, rubbing Sans' hip in soothing circles.  
  
"ah... i'm, fuck, i'm good," Sans gasped out, trembling. "please, i... oh stars, i need you, please move," he begged and Gaster moaned as Sans clenched pointedly around him.  
  
"Very well," Gaster managed to say in what was surely an infuriatingly mild tone, as if he wasn't buried deep in Sans' hot, wet, _tight_ pussy. Sans opened his mouth to beg again, but Gaster lightly rolled his hips, making Sans gasp and moan instead. Soon enough, he'd set up a gentle rocking motion, keeping his movements shallow and slow. Sans seemed to appreciate that as he panted, clinging to Gaster as he moved with the elder.  
  
Eventually, though, that wasn't enough. Tears of frustrated arousal lined the edges of Sans' sockets as he moaned desperately. He wanted, _needed_ to cum, but it wasn't enough. "faster, harder, oh stars, please," he begged. Gaster growled in return, but instead of being intimidating, it just added fuel to the fire burning in Sans' bones and he moaned. Gaster growled again before pulling out almost completely and slamming back in. Sans cried out, voice raising beyond what it was normally capable of as Gaster's new pace quickly sent him tumbling over the edge.  
  
Gaster's pace stuttered as Sans tightened impossibly around him, making it hard to move. He didn't want to hurt Sans, so he shifted back to a shallow rolling motion as he let Sans ride out his high. He was expecting Sans to be exhausted again after he came down, but Sans defied his expectations by moaning and clinging, begging for more.  
  
It was at that moment that Gaster realized that not only was this heat going to be rough on Sans but that before he'd taken him, Sans' heat must not have been entirely set in. Now that it was, it seemed it wasn't going to release the smaller monster anytime soon. Gaster growled softly again, leaning down to kiss Sans as he started thrusting harder and faster again.  
  
Sans whined into the kiss, clinging tightly as his oversensitive magic was roughly pounded into. It felt so good that it nearly hurt, but he couldn't think past the absolute need burning through him. His world had condensed to himself, Gaster, and the heat burning in his soul, which pulsed brightly in his chest cavity, sending waves of love and want and need to Gaster's soul. Gaster's answered in kind, bringing tears to Sans' sockets and causing his soul to physically manifest.  
  
He knew the moment Gaster noticed, felt the pulse of curiousity and desire and 'pleaseletmetouchit'. Sans keened, fumbling for one of Gaster's hands, guiding it inside his ribcage, sent an answering pulse of 'pleasetouchme', and then his world condensed further as phalanges brushed the surface of his soul. Everything narrowed to the cock still pounding into him and the hand gently wrapping around his soul, drawing it from his ribcage. He felt Gaster's curiousity shift to awe, sensed Gaster's absolute admiration for him, the waves of answering desire and love and Sans started to cry for real, clinging desperately to Gaster in every way he could as everything he was lit up in intense pleasure.

\--------------------------------------------

Sans groaned softly as consciousness slowly returned. In the aftermath of everything, he felt exhausted and didn't want to wake up. Heat lingered in his bones, but it was completely gone from his soul already, the culmination of his being back where it belonged as if it had never been removed. He groaned again, trying to figure out what had woken him, but then he felt a soft, warm cloth against his femur and realized that must have been it.  
  
Slowly, he opened his sockets, weakly pushing himself up enough to see Gaster seated on the edge of the bed, carefully cleaning Sans' legs. Instead of being annoyed to have been woken up, Sans felt a pulse of happy warmth at the care Gaster was granting him. He hummed happily, this time drawing Gaster's attention away from his self-appointed task. "Sans. I am sorry. I did not mean to wake you," the elder murmured softly, undeniable fondness in his tone as well as regret for having woken the younger skeleton.  
  
Sans smiled dopily, shaking his head. "nah... it's fine," he replied, humming happily again as he flopped back to the mattress before letting out a content, satiated sigh. Gaster chuckled softly, continuing to clean Sans up. By the time he was done, Sans had drifted off into a deep sleep, a dopy smile still lingering.  
  
There would be much to talk about when Sans woke for real, but for now, Gaster got Sans into the bed properly, slid in beside him, and cuddled the smaller monster close as he too, fell asleep.

**Notes for the Chapter:**

> once Sans wakes up, they talk and negotiate their relationship. they agree to start dating and see where it takes them. Gaster finds out soon after they start dating that Sans is the new Judge when Sans is called to the castle until he can learn to control the magic properly. While he still feels a little awkward about the huge age gap, the fact that Sans _seriously_ outranks him settles his remaining unease over the power imbalance and eventually he gives in to what they both want and soul bonds with Sans.


End file.
